With the spread of computer networks such as broadband and wireless LAN, the products called as digital information equipment having a communication function (digital home appliances, hereinafter) have been gradually widespread. Moreover, with the start of terrestrial digital broadcasting and the halt of analog broadcasting, it is predicted that TVs, set-top boxes (STB), DVD recorders, etc., for digital broadcasting will be further widespread in the near future. If a plurality of digital home appliances are connected to a network, users can view or listen to contents via a network, thereby enhancing usability.
Here, contents intend to various types of digital data, i.e. moving-picture data such as MPEG2 or MPEG4, audio data, stream data, text data, still-picture data, etc. Contents composed of these types of data have a feature in that it can be easily copied with no degradation. Therefore, special care is needed for the copyright of contents. For example, a regulation of Japanese digital broadcasting stipulates that a recorder can record contents received via a broadcast wave in internal equipment up to ten times in total. This is commonly called “dubbing 10”. Moreover, the current regulation stipulates that when equipments which received a broadcast wave output streaming contents to a network, “the number of streams to be simultaneously output be less than eight for each receiver” with respect to transmission of generation management information.
Incidentally, various proposals have been made in order to protect copyright of contents and enhance usability of contents.
As described above, according to the current regulation, equipment for receiving Japanese digital broadcasting can record streams in internal equipment up to ten times and output eight streams at the maximum to a network. Under the current regulation, if it is supposed to store eight streams output to a network in each of separated recording apparatuses, eight copies can be made, and the number of copies made in the equipment which received Japanese digital broadcasting under the regulation of dubbing 10 is added. As a result, 18 copies can be made in total at the equipment itself and the other equipment. As described above, under the current regulation, users cannot freely make 18 copies. More specifically there is a restriction on the storage place in that 10 copies at the maximum are permitted for the user's equipment and eight copies at the maximum are permitted for the other equipment. In this way, usability under the current regulation is not sufficient.